阅读说明：本技术 用于气体的压缩、膨胀和/或存储的方法、系统和设备 (Method, system and apparatus for compression, expansion and/or storage of gases ) 是由 拉菲克·巴胡米 帕特里克·鲍曼 多米尼克·施纳尔维尔 于 2019-05-16 设计创作，主要内容包括：该方法用于管理作为能量存储系统的组件的蓄压器(1),能量存储系统由工作机(4)、集水池(7)、置换装置(6)和蓄压器(1)组成,用于存储加压的气态介质。蓄压器(1)部分地填充有液体介质,以便能够用液体介质控制气体存储量。将压缩气体(3)输送到蓄压器(1)中涉及移除液体(2)。从蓄压器(1)中移除压缩气体(3)涉及输送液体(2),使得根据需要将存储压力保持在控制之下,特别是保持恒定。为此,通过置换装置(6)从蓄压器(1)中移除一个单位的液体(2)而将加压的单位气体(3)引入蓄压器(1),反之亦然。本发明的方法和布置使得可以用可控压力的加压气体(3)完全填充蓄压器(1)以及完全排空压力存储单元(1),这导致了蓄压器容积的利用的改善,并且因此增加了能量存储系统的能量密度。该方法还使得能够在恒定的操作点操作能量存储系统,因此提高了单独的组件和整个系统的效率,并且最大程度地缩短蓄压器(1)中的压缩和膨胀过程。(The method is used for managing an accumulator (1) as a component of an energy storage system, which consists of a working machine (4), a collecting tank (7), a displacement device (6) and the accumulator (1), for storing a pressurized gaseous medium. The pressure accumulator (1) is partially filled with a liquid medium, so that the amount of gas stored can be controlled with the liquid medium. The delivery of compressed gas (3) into the pressure accumulator (1) involves the removal of liquid (2). The removal of compressed gas (3) from the pressure accumulator (1) involves the delivery of liquid (2) such that the storage pressure is kept under control, in particular constant, as required. For this purpose, pressurized unit gas (3) is introduced into the pressure accumulator (1) by removing one unit of liquid (2) from the pressure accumulator (1) by means of a displacement device (6), and vice versa. The method and arrangement of the invention make it possible to completely fill the accumulator (1) and completely empty the pressure storage unit (1) with a pressurized gas (3) of controllable pressure, which results in an improved utilization of the accumulator volume and thus in an increase of the energy density of the energy storage system. The method also enables operating the energy storage system at a constant operating point, thus improving the efficiency of the individual components and the entire system and minimizing the compression and expansion process in the accumulator (1).)

1. A method for managing a pressure storage system having at least one pressure storage tank, i.e. on the one hand for filling the pressure storage tank with compressed gas and/or on the other hand for withdrawing the compressed gas from the pressure storage tank, wherein the pressure storage tank (1) is partially filled with a liquid (2) and the remaining volume is filled with compressed gas (3), characterized in that the filling of the pressure storage tank (1) with unit compressed gas (30) is accompanied by withdrawing unit liquid (20) from the pressure storage tank (1), whereby the withdrawn unit liquid (20) is used for displacing the unit compressed gas (30) into the pressure storage tank (1) at low power when required by means of a transfer device (6), which transfer device (6) consists of at least one transfer mechanism (61) and at least one transfer container (60), vice versa, the withdrawal of unit compressed gas (30) from the pressure storage tank (1) is accompanied by the filling of unit liquid (20) into the pressure storage tank (1), whereby the unit liquid (20) is used to withdraw the unit compressed gas (30) from the pressure storage tank (1) at low power when required by the transfer means (6).

2. A method for operating a pressure storage system according to claim 1, wherein a working machine (4) is also used for compressed gas (3) and vice versa, the compressed gas (3) being expanded by releasing mechanical energy, which is accordingly provided or absorbed by a drive or an output (8), and wherein this working machine (4) is fluidically connected to a gas source/tank (5), characterized in that a fluidic connection (11, 12) is established from the transfer device (6) to the working machine (4) and/or the pressure storage tank (1) on the gas side, if necessary, and a fluidic connection (13, 14) is established to the pressure storage tank (1) and/or a water collection tank (7) on the liquid side, if necessary, by opening a respective valve (64, 65), in order to bring liquid (2) between the transfer device (6) and the pressure storage tank (1) or the water collection tank (7) Can be transferred and at the same time in order to enable the transfer of gas (3) between the transfer device (6) and the pressure storage tank (1) or the working machine (4).

3. Method for managing a pressure storage system according to one of the preceding claims, wherein the transfer device (6) is in particular operated with a plurality of individual or combined transfer vessels (60a, 60b, 60c), which individual or combined transfer vessels (60a, 60b, 60c) are mechanically or fluidically connected to each other and are arranged in parallel and/or in series.

4. Method for managing a pressure storage system according to one of the preceding claims, wherein the transfer device (6) is used to compress or expand gas, respectively, by selectively transferring liquid between the transfer device (6) and the pressure storage tank (1), sump (7) or within the transfer device (6) itself, i.e. between transfer vessels (60a, 60b,/60 c).

5. Method for managing a pressure storage system according to one of the preceding claims, wherein the liquid located inside the transfer device (6), the pressure storage tank (1) or the sump (7) is used as a heat transfer medium and/or a heat storage medium to provide heat to or remove heat from the gas before, during and/or after compression or expansion of the gas, preferably inside a moving container (60a, 60b, 60 c).

6. Method for managing a pressure storage system according to one of the preceding claims, wherein the heat exchange between the gas and the liquid within the transfer vessel (60a, 60b, 60c) is increased by a heat accumulator (69) to transfer heat from the gas to the liquid or vice versa.

7. Method for managing a pressure storage system according to one of the preceding claims, wherein the pressure storage tank (1) consists of at least two separate pressure vessels (101, 102) and during charging of a first pressure vessel (101) with the compressed gas (3) the liquid (2) is displaced to a second pressure vessel (102), after charging of the first pressure vessel (101) the second pressure vessel (102) is charged with the compressed gas (3) and only during charging of the last pressure vessel the liquid (2) is displaced to a sump (7), wherein when removing the compressed gas (3) from the pressure storage tank (1) the procedure is the same as the separate pressure vessels (101, 102) are emptied one after the other.

8. An apparatus for operating a pressure storage system for performing a process according to one of claims 1 to 7, the plant has at least one pressure storage tank (1), a sump (7) partially filled with liquid and partially filled with gas, a working machine (4) for converting compressed gas into mechanical energy, and vice versa, connected to a gas source/tank (5), characterized in that a transfer device (6) is present, which transfer device (6) is in fluid connection (13, 14) on the liquid side with the pressure storage tank (1) and the collecting basin (7), and is fluidically connected (11, 12) to the working machine (4) and the pressure accumulator tank (1) on the gas side, wherein the transfer device comprises at least one transfer container (60) alone or in combination, and a valve for selectively closing one or more fluid connections (11-14) for gas or liquid.

9. An apparatus for operating a pressure storage system for performing the process according to any one of claims 1 to 7, characterized in that the pressure storage system comprises at least the following components:

at least one pressure storage tank (1) partially filled with liquid (2) and compressed gas (3), whereby the two media are in open abutment with each other or separated from each other by suitable separation means, i.e. by gas bubbles, pistons or membranes, and a sump (7),

-a transfer device (6) consisting of at least one transfer container (60) and a transfer mechanism (61) alone or in combination, wherein the media contained in the transfer container (60) are openly adjacent to each other or separated from each other by suitable separation means in the form of bubbles, pistons or membranes, said transfer mechanism (61) being used to displace the liquid within said transfer device (6) when required at low power, i.e. between transfer containers and/or between said transfer device (6) and said pressure storage tank (1) or said sump (7),

-a fluid connection (13) between the transfer device (6) and the pressure storage tank (1) for displacing fluid between the transfer device (6) and the pressure storage tank (1) at low power when required,

-a fluid connection (14) between the transfer device (6) and the sump (7) for displacing fluid between the transfer device (6) and the sump (7) at low power when required,

-a fluid connection (12) between the transfer device (6) and the pressure storage tank (1) for displacing gas between the transfer device (6) and the pressure storage tank (1) when required at low power,

-a fluid connection (11) between the transfer device (6) and the working machine (4) and/or the gas source/tank (5) for displacing gas between the transfer device (6) and the working machine (4) and/or the gas source/tank (5) at low power when required,

controllable valves, defining the flow direction of the fluid and gas during operation,

a working machine (4) for compressing and/or expanding gas,

-an input/output driver (8) for converting energy from any form of energy into mechanical energy for driving the working machine (4) and, if necessary, driving the transfer mechanism (61), and vice versa, adapted to receive mechanical energy from the working machine (4) and, if necessary, from the transfer mechanism (61), and to convert and output in any form of energy.

10. The apparatus for operating a pressure storage system according to one of claims 8 or 9, characterized in that the transfer mechanism (6) is integrated into the working machine (4) or combined with the working machine (4) or replaces the working machine (4), or forms one to several stages of the working machine (4).

11. Apparatus for operating a pressure storage system according to one of claims 8 to 10, characterized in that the transfer mechanism (61) has a separate drive/output or a drive/output (8) coupled to the working machine (4) and consists of a piston or a pump.

Background

The method is used for managing a pressure storage tank as a component of an energy storage system, the pressure storage tank consisting of a working machine, a sump for receiving liquid, a transfer device and a pressure accumulator for storing a pressurized gaseous medium. The accumulator is filled to a certain extent with a liquid medium in order to be able to control the gas storage volume, so that the accumulator is filled with pressurized gas, with the withdrawal of liquid. The extraction of the pressurized gas from the pressure storage tank is accompanied by the filling of the liquid, and in particular, the pressure in the pressure storage tank is kept constant by introducing the unit pressurized gas into the pressure storage tank by the transfer means by extracting the unit liquid from the pressure storage tank. Conversely, the unit liquid introduced into the pressure storage tank by the transfer means transports the unit gas to be removed from the pressure storage tank out of the pressure storage tank. This method or arrangement makes it possible to completely fill and evacuate the pressure storage tank with pressurized gas, which results in a better utilization of the pressure storage volume and thus an increase in the energy density of the energy storage system. In addition, pressure fluctuations in the pressure storage tank are minimized, which reduces the load on the pressure storage tank and minimizes the amount of heat flowing into and out of the pressure storage tank. It is possible to optimize the working machine for one working point independently of the filling level of the pressure storage tank, which brings about a further advantage.

Energy storage systems, such as batteries or pumped storage power stations, are used to store energy that is available again at times of high energy demand. Energy storage builds in conventional energy production and is increasingly required for the generation of renewable electricity in terms of preventing the generation of excess capacity for power generation and distribution. For example, the ability to store energy may be required because the solar and wind energy generated is dependent on local weather conditions and thus may not be able to accommodate current energy demands, or may not be able to accommodate current energy demands at all.

Storage systems that store energy in the form of pressurized gas use energy generated during off-peak hours to compress a gaseous medium (primarily ambient air) and store the pressurized gas in a pressurized storage tank. The energy stored in the pressure storage tank can be recovered by driving an expander (e.g. driving an electrical generator) using the pressurised gas. This concept is referred to in various forms as CAES and is an abbreviation for compressed air energy storage. In the following description of the invention the term "air" may be used, but of course a wide variety of gaseous media may be used according to the invention, such as natural gas taken from a pipeline network and stored at a higher pressure in a pressure storage tank, which is later expanded to the pressure of the pipeline network. Typically, the gas withdrawn from the first container is compressed by increasing the pressure and stored in a second container having a higher pressure level than the first container, and/or the gas withdrawn from the second container is expanded and fed into a third container, which has a lower pressure level than the second container, which may also be the first container.

During the compression of air, almost all of the used compression energy is transferred into heat, which can be removed from the compressed air during or after the compression in order to store the compressed air at moderate temperatures. If heat dissipation occurs primarily during compression, the heat of the compressed air is less than the heat that would be dissipated from the air only after compression. Depending on the maximum temperature difference of the air (difference between the air temperature at the beginning of compression and the highest temperature during compression), isothermal compression (large heat dissipation during compression, with the temperature difference kept at a minimum), multidirectional compression (partial heat dissipation during compression, with the temperature difference between the minimum and maximum difference) or adiabatic compression (large heat dissipation after adiabatic compression, with the maximum temperature difference) can be said. The same is true for the expansion of the compressed air, except that the heat flow is reversed here. If heat is added to the compressed air during expansion, the air is cooled less than if heat was added to the air just before or after expansion, thereby subjecting the air to the greatest temperature difference. The design differences of the different CAES concepts are where and at what temperature difference the heat dissipation occurs before, during and/or after compression, where the heat of compressed air expansion comes from and at what temperature difference the heat is provided to the air before, during and/or after expansion of the air.

Apart from the type of compression and expansion (isothermal, polytropic, adiabatic/single-stage or multi-stage/with reversible working machine, or respectively compressor and expander, under fuel combustion), the CAES concept differs in the type of pressure storage concept used. A distinction is made here as to whether a constant or variable pressure storage volume is used. If a constant pressure storage volume is charged or discharged with compressed air, the pressure of the compressed air in the pressure storage varies linearly with the storage amount of the compressed air. This requires a working machine which can be adapted to the storage pressure and which usually prevents complete emptying of the pressure storage tank, since the working machine can only work within a certain pressure range. Therefore, a certain amount of compressed air must always remain in the pressure storage tank in order not to fall below the minimum working pressure of the working machine. Depending on the pressure storage tank, the pressure may fluctuate only within a certain range so as not to overload the pressure storage tank, which also makes it impossible to completely empty the pressure storage tank. The heat flow into and out of the pressure storage tank is also not negligible, since the compressed air in the pressure storage tank is also compressed or expanded during filling and emptying.

The pressure change of the compressed air in the pressure storage tank can be controlled when loading and unloading the pressure storage tank having a variable tank volume. The purpose of this is generally to keep the pressure of the air in the pressure storage tank constant or at least within a certain range during filling or draining of the pressure storage tank. The constant storage pressure makes it possible to completely fill and empty the pressure storage tank with compressed air without the operating parameters of the working machine having to be adjusted to the filling level. Furthermore, there are no or only minimal pressure fluctuations on the pressure storage tank, which reduces the load on the pressure storage tank. The amount of heat flowing into and out of the pressurized storage tank is also minimized.

During the implementation of different concepts, different technical problems arise, as shown below. For example, DE19803002892/US4392354 discloses an arrangement of a partly water-filled pressure storage tank, in which the pressure of the compressed air in the pressure storage tank is kept constant by a water column. In order to absorb the discharged water when the pressure storage tank is filled with the compressed air, a catch basin must be installed at the upper end of the water column. For example, at a storage pressure of 60bar, the water column must be 600m higher, which leads to geographical dependence on the pressure storage tank.

US20120174569a1/US9109512B2 shows an arrangement with a high sump and a hydraulically driven two-stage piston compressor/expander. When the pressure storage tank is emptied, the hydrostatic pressure of the water column will maintain a minimum pressure in the pressure storage tank. In order for the pressure storage tank to reach a higher pressure level than the height difference between the pressure storage tank and the sump allows, the sump only needs to be isolated from the pressure storage tank. When the pressure storage tank is emptied, the sump will be reconnected to the pressure storage tank as soon as the pressure in the pressure storage tank corresponds to the hydrostatic pressure of the water column, and the pressure will be kept above the minimum storage pressure when the pressure storage tank is further emptied. Here, there is also a geographical dependence of the higher-lying catchments.

US20120305411a1/US8801332B2 shows a construction of a pressure storage tank, which is installed under water. At the lower end of the pressure storage tank there is an opening through which water is forced into the pressure storage tank by hydrostatic pressure. Compressed air is directed into or out of the tank by a working machine located above the water level. There are also other versions of underwater (constant) pressure storage tanks, for example in the form of an inflatable balloon, which is kept underwater. All these configurations depend on the geographical location and the pressure tank will be subjected to buoyancy by the stored compressed air, which must be compensated for in order to keep the pressure storage tank under water.

Furthermore, from the prior art a system is known according to WO1993006367a1, in which two washed-out salt caverns are partially filled with liquid and have a fluid connection on the liquid and gas side. As deeper caverns are filled with compressed air, pressure fluctuations in the caverns are reduced by simultaneously removing liquid. The system relies on a higher catch basin and the two caves must be located at different depths, which corresponds to geographical dependence. If the existing height difference is too small, i.e. the hydrostatic pressure is lower than the pressure in the lower cavern, the pressure in the cavern can be adjusted with a liquid motor or liquid pump. The fluid motor or fluid pump reduces the overall efficiency and power input or output of the system. In addition, this is a closed air system, where the air hermetically sealed is compressed to store energy, seen from above the two caverns, which has a number of disadvantages. At the same operating pressure, the energy density of closed air systems is generally much lower than open air systems because the total air volume is predetermined and therefore no additional air volume can be introduced into the system. This results in a system with a lower energy density at the same operating pressure. On the other hand, in an open air system, the amount of air can be repeatedly added or removed from the system through a cyclic process.

In order to eliminate geographical dependency or required height differences, the pressure in the pressure storage tank may be controlled with liquid by filling the pressure storage tank with compressed air and expanding the liquid from the pressure storage tank to a sump by a liquid motor, which does not have to have a height difference, as shown in WO2012160311a 2. Conversely, when compressed air is removed from the pressure storage tank, liquid is pumped from the sump into the pressure storage tank to control the pressure in the pressure storage tank. This has the disadvantage that the overall efficiency and overall power consumption of the system (relative to the installed air compressor/expander power and liquid motor/pump power) becomes small, since when compressing air and filling the pressure storage tank, liquid must be expanded from the pressure vessel if at the same time; vice versa, when inflating air, liquid must be pumped into the pressure storage tank at the same time.

The teachings of WO2008023901a1/US20090200805a1/US7663255B2 eliminate the problems of geographical dependence and power and efficiency reduction by additional liquid pumps/motors, because in addition to the first pressure storage tank, which is partially filled with liquid and connected to the air compressor/expander, the second pressure storage tank must be available, which in turn must be partially filled with liquid. The second pressure reservoir tank is hermetically sealed on the gas side and is connected to the first pressure reservoir tank via a line, so that, when the first pressure reservoir tank is filled with compressed air, a liquid pump built into the line pumps liquid from the first pressure reservoir tank to the second pressure reservoir tank, where the enclosed gas is compressed. When the first pressure tank is empty, i.e. filled with liquid, the gas trapped in the second pressure tank is at the minimum system pressure. When the first pressure storage tank is filled with compressed air and liquid has been pumped into the second pressure storage tank, the pressure in the second pressure tank is several times higher than the pressure in the first pressure tank. The second pressure storage tank is almost unable to store energy with respect to the maximum working pressure and its volume, which makes the system expensive.

Disclosure of Invention

The object of the present invention is therefore to create a structurally simple, inexpensive and reliable pressure storage system which is capable of controlling the pressure of compressed air in a pressure storage tank during the loading or unloading of the pressure storage tank with compressed air and liquid.

First of all, it is necessary not to rely on the hydrostatic pressure of the column of liquid (higher level sump or underwater storage tank) or any other difference in height between the two tanks

Secondly, no gas-tight sealed gas cushion is used in the one or more pressure storage tanks,

thirdly, without the above-mentioned drawbacks of reduced power and efficiency,

and has the advantage of high energy density in the system and has good control of heat flow into and out of the system to supplement the actual pressurized storage system with efficient and flexible heat or cold energy generation.

This object is solved by a pressurized storage system according to the features of the process of claim 1 and according to the features of the apparatuses for carrying out the process of claims 8 and 9.

Controlling the characteristics of the pressure in the pressure storage tank during filling with pressurized gas or discharging compressed gas with liquid, in particular keeping the pressure constant,

first, without relying on the hydrostatic pressure of the column of liquid (higher level sump or underwater storage tank), or any other difference in height between the two tanks being necessary,

secondly, no gas-tight sealed gas cushion is used in the one or more pressure storage tanks,

thirdly, without the above-mentioned drawbacks of reduced power and efficiency,

in the following, we also designate "low power on demand" filling of the pressure store with compressed gas, or "low power on demand" withdrawal of compressed gas from the pressure store, or generally "low power on demand" moving compressed gas into or out of the pressure store.

The fact that the pressure storage tank is filled with compressed air with liquid from the pressure storage tank being withdrawn, and at the same time the withdrawn liquid is used to move compressed air into the pressure storage tank, means that the pressure in the pressure storage tank can be controlled, in particular kept constant. It is also possible to introduce compressed air into the pressure storage tank without further compressing the compressed air in the pressure storage tank. After the transfer process of introducing the compressed air into the pressure storage tank, the amount of liquid removed from the pressure storage tank is transferred to the sump so as to move the liquid back into the pressure storage tank when the compressed air is removed from the pressure storage tank.

In order to fill or empty the pressure storage tank with any design of working machine (compressor/turbine), a transfer device is required in addition to the pressure storage tank and the catchment basin. The transfer device may additionally be used as a compression stage or a pressure expansion stage. The transfer devices may also be arranged in parallel and/or in series. Since the transfer device can also be used as a compressor/expansion stage, no additional working machine (compressor/turbine) is required, or the transfer device can be used instead of at least one compressor/expansion stage in the working machine.

If it is desired to store the heat of compression and reuse that heat during later expansion to prevent the system from being too cold, the liquid in the system can be used as a heat buffer. The heat of compression may also be used in other ways (e.g., in buildings for hot water and heating) and returned to the system from the environment for expansion, and vice versa, the heat of compression may be released to the environment, and the heat of expansion may be returned to the system from other sources (e.g., to cool the building). Of course, the heat of compression may be used elsewhere and the heat of expansion may be absorbed from the object to be cooled. This is justified because the heat of compression can be released at a different temperature level than the one at which the heat for expansion is fed back into the system.

The constant pressure in the pressure storage tank means that the compression or expansion process in the pressure storage tank itself is eliminated, so that the heat flow into and out of the pressure storage tank is also eliminated, and all the compression heat and/or expansion cold can be dissipated at the compressor or expander. By minimizing the amount of heat flowing into and out of the pressure storage tank, this will result in the pressure storage system incorporating efficient heat or cold energy generation. So-called triple power systems, i.e. combined thermoelectric and cold coupling, make it possible to couple the sectors of electricity, heat and cold production.

In order to eliminate a given dependency between heat generation and filling of the pressurized storage tank and between cold energy generation and emptying of the pressurized storage tank and to achieve sufficient flexibility in meeting the requirements of electricity, heat and cold energy, the pressurized storage system must comprise at least two compressor/expansion stages arranged in parallel. This allows the generation of heat or cold energy independent of the liquid level of the pressure storage tank by simultaneously compressing and expanding air.

Preferably, the transfer vessel is partially filled with a solid serving as the mass of the regenerator. For example, a metal or ceramic, preferably one having a large surface area compared to the volume, may be used to dissipate heat into or out of the air, which is then continuously absorbed or released by the liquid or by a heat exchanger.

It should be understood that the liquid may be in direct contact with the air or may be separated from the air by various media separation devices (e.g., bubbles, pistons, membranes, etc.). The fluid may be displaced directly by a fluid pump/motor or piston, for example by a hydraulic or pneumatic piston or a crankshaft with connecting rods.

Drawings

The invention is described below and its function is explained using the drawings.

It shows that:

fig. 1 is a schematic arrangement of a pressure storage system with a transfer device. In order to use the transfer device according to the invention, the input and output drives, the pressure storage tank and the catchment basin must be available;

FIG. 2 is an exemplary design of a transfer device and schematic arrangement of the pressure storage system of FIG. 1;

fig. 2a to 2z are all different modes of operation of the arrangement of fig. 2;

fig. 2a to 2f show the "compressed mode without post-compression" operating mode.

Fig. 2g to 2m illustrate the operation mode of "compression mode with post-compression".

FIGS. 2 n-2 s illustrate the "expansion mode without pre-expansion" mode of operation;

FIGS. 2t to 2z illustrate the "expansion mode with pre-expansion" mode of operation;

fig. 3a to 3c show possible embodiments of a transfer device with one or more separate and/or combined gas and liquid transfer containers and a transfer mechanism designed as a piston;

FIG. 3a is a combined gas and liquid transfer vessel;

FIG. 3b is a combined gas and liquid transfer vessel and a separate liquid transfer vessel;

FIG. 3c is a separate gas and liquid transfer vessel;

fig. 4 is a possible parallel arrangement of two combined transfer containers 60a, 60b, a separate transfer container 60c and a piston with a piston rod as the transfer mechanism 61;

FIG. 5 is another possible parallel arrangement of transfer vessels 60a and 60b and a piston as a transfer mechanism 61;

FIG. 6 is a possible parallel arrangement of transfer vessels 60a and 60b and a liquid pump as transfer mechanism 61;

fig. 7 is a possible parallel and serial design of the transfer vessel and the liquid pump as transfer means 61a and 61b, whereby the transfer process is applied between the second stage and the pressure storage tank 1 and between the first stage and the second stage;

fig. 8 is a separating device 31 for separating the liquid 2 from the compressed gas 3 in the pressure storage tank 1;

fig. 9 is a possible arrangement of the heat accumulator 69 and/or the heat exchanger 68 in the transfer vessel 60;

FIG. 10 is the energy storage system of FIG. 1, except that the catch basin 7 is brought to a pressure level between the pressure of the gas source/sink 5 and the pressure of the pressure vessel 1;

fig. 11 combines pressure vessels 101, 102.

Detailed Description

Fig. 1 shows a pressure storage tank 1, partially filled with a liquid 2 (here water) and a compressed gas 3 (here air), whereby the gas and the liquid are in direct contact or separated by means (not shown in fig. 1). Also shown is a working machine 4, which working machine 4 is in fluid connection with a gas source/tank 5 (here atmospheric air) and is capable of taking gas from the gas source 5 to compress the gas and deliver the gas to the pressure storage tank 1 via a transfer means 6 and/or from the pressure vessel 1 via the transfer means 6 to expand the gas and supply the gas to the gas tank 5. The working machine 4 can be composed of a compressor and an expander and the necessary drive 8 or output 8 alone or a combined compressor/expander, which can both compress and expand gas, whereby the working machine 4 can also be constructed in a multistage design. The drive 8 or output 8 of the working machine 4 is, for example, an electric motor or generator connected to a power grid 9. When compressing the gas, power is drawn from the grid 9, and when expanding the gas, power is delivered to the grid 9.

The transfer device 6 is characterized by the fact that on the gas side a fluid connection 11, 12 can be established to the working machine 4 and/or the pressure reservoir 1, and on the liquid side a fluid connection 13, 14 can be established to the pressure reservoir 1 and/or the collecting sump 7, i.e. in such a way that liquid can be fed into the pressure reservoir 1 or the collecting sump 7 or out of the pressure vessel 1 or the collecting sump 7 and at the same time the gas in the transfer device 6 or the pressure reservoir 1 is transferred, compressed or expanded.

By moving liquid from the pressure storage tank 1 or the sump 7 into the transfer means 6, the gas in the transfer means 6 can be transferred into the pressure storage tank 1 or the working machine 4 and/or the gas can be compressed by the transfer means 6 depending on whether the gas in the transfer means 6 is connected to the working machine 4 or the pressure storage tank 1 via a fluid connection 11, 12 or whether the connection 11, 12 is interrupted. The flow direction of the flow generated by the transfer device 6 and/or by the working machine 4 via the fluid connections 10, 11, 12, 13, 14 is shown by arrows.

By transferring liquid from the transfer device 6 into the pressure storage tank 1 or the sump 7, gas from the pressure storage tank 1 or from the working machine 4 can be sucked into the transfer device 6 or moved upwards and/or the gas in the transfer device 6 can be expanded by the transfer device 6, depending on whether there is a fluid connection 11, 12 or whether the connection 11, 12 to the working machine 4 or the pressure storage tank 1 is interrupted or not.

In case there is a fluid connection 11 between the transfer device 6 and the work machine 4, there may also be a connection to the gas source/tank 5 or to a gas at a pressure level between the pressure of the pressure storage tank 1 and the pressure of the gas source/tank 5, or to a gas at or above the pressure level of the pressure storage tank 1, or in general at any pressure level.

The arrangement of fig. 1 makes it possible to drive the working machine 4 via the power grid 9 in order to compress gas and to feed the compressed gas to the transfer device 6, in which transfer device 6 the fed gas can be either compressed or transferred into the pressure storage tank 1, or to transfer the supplied gas from the transfer device 6 into the pressure storage tank 1 without further compression of the gas. According to the invention, the pressure in the pressure storage tank 1 or the amount of gas stored in the pressure storage tank 1 can be controlled by taking the liquid transferred by the transfer means 6 from the pressure storage tank 1 or from the sump 7 for carrying out the transfer and/or compression process when the compressed gas is moved from the transfer means 6 into the pressure storage tank 1.

The arrangement of fig. 1 also allows compressed gas from the pressure storage tank 1 to be transferred to the transfer device 6 and/or expanded into the latter in order to expand the compressed gas and then make it available to the working machine 4 for further expansion, or to make the compressed gas available to the working machine 4 for expansion without prior expansion, the compressed gas in turn driving a generator 8, with which generator 8 electric power is delivered to the grid 9. According to the present invention, when moving compressed gas from the pressure storage tank 1 into the transfer device 6, the pressure in the pressure storage tank 1 or the amount of gas stored in the pressure storage tank 1 can be controlled by transferring liquid from the transfer device 6 into the pressure storage tank 1 or the sump 7.

Fig. 2 shows a possible design of the transfer device 6, which consists of a transfer container 60 for providing a transfer volume, whereby this volume can be provided by a separate container, but can also be integrated in the working machine 4, or can exist as a pipe volume between the working machine 4 and the pressure storage tank 1. Furthermore, the transfer device comprises a transfer mechanism 61, which is designed here as an example as a liquid pump 61, whereby in general the liquid pump 61 merely indicates the flow direction, rather than the compression or expansion, and has valves 62, 63, 64, 65 which allow establishing [ ] or interrupting [ X ] the fluid connections 11, 12, 13, 14 between the transfer device 6 and the working machine 4, the pressure reservoir 1 and/or the sump 7. In the following, it is generally not explicitly discussed which valve establishes or interrupts the fluid connection at this point in time, as this is evident in the figures, and the established fluid connection is also characterized by the direction of flow of the fluid.

It should also be mentioned at this point that the transfer mechanism 61 must of course also be driven or braked, and that this can be achieved in various ways, for example by a mechanical connection to the working machine and its drive and output, or correspondingly by a separate drive or output. This mechanical connection or this input and output is not shown in fig. 2 and 2a to 2z, since the liquid pump 61 is only used as an example of the displacement mechanism 61. In the following, it may generally be assumed that both input and output power are available for the displacement mechanism 61 (here a liquid pump), and that, if desired, additional valves or devices may be used, for example, to reverse the direction of action of the displacement mechanism 61 or to cancel or adjust its action partially or completely.

The various modes of operation resulting from the arrangement of fig. 2 are explained on the basis of fig. 2a to 2z, whereby the representation at different points in time describes the state or current process in the system and will be understood schematically.

Hereinafter, the procedure shown in fig. 2a to 2f is designated as "compression mode without post-compression". Compressed mode is identified by the fact that: the flow direction of the gas is directed (at least on a time average) from the gas source 5 to the working machine 4. This means that the working machine 4 is driven to compress gas and draw power from the grid 9. Fig. 2a shows that the transfer process is started by transferring the unit of compressed gas 30 located in the transfer vessel 60 into the pressure storage tank 1. This is accomplished by pumping or transferring the unit liquid 20 from the pressure tank 1 into the transfer vessel 60, respectively, by the liquid pump 61, and the liquid level of the transfer vessel 60 is raised, and therefore, the unit compressed gas 30 is pressed into the pressure tank 1, wherein the unit compressed gas 30 replaces the volume released by the unit liquid 20 just taken out of the pressure tank 1. This process is shown in fig. 2a to 2c in three successive time steps. Since the unit liquid 20 and the unit compressed gas 30 are at the pressure level of the pressure storage tank 1 during this process, the liquid pump 61 only needs to apply a small amount of power (e.g., flow loss, gravity, buoyancy) to move the unit liquid 20 and thus the unit compressed gas 30 within a certain time.

Fig. 2d to 2f show a continuation of the process of fig. 2a to 2c, moving the unit liquid 20 in the transfer container from the transfer container 60 to the sump 7. For this purpose, the fluid connection 12 of the transfer container 60 to the pressure storage tank 1 is interrupted and a fluid connection 11 is established between the working machine 4 and the transfer container 60, so that gas can flow from the working machine 4 into the transfer container 60 or can be sucked in. Furthermore, a fluid connection 14 is established between the transfer container 60 and the sump 7, so that the transfer mechanism 61 can transfer the unit liquid 20 from the transfer container 60 into the sump 7. It is relevant which pressure level of gas flows from the working machine 4 into the transfer container 60 or is sucked into the transfer container 60. If this is done with, for example, gas at the pressure level of the gas source 5, and the liquid in the sump 7 is also at the pressure level of the gas source 5, then the liquid pump 61 need only apply a small amount of power (e.g., flow loss, gravity, buoyancy) in turn to pump the unit liquid 20 from the transfer container 60 into the sump 7 over a period of time. During this process, the higher the pressure difference between the liquid in the transfer vessel 60 and the liquid in the sump 7, the more power the liquid pump 61 must apply to pump (compress) or brake (expand) the liquid, depending on which pressure level is higher in the sump 7 or in the transfer vessel 60. If the gas contained in the transfer vessel 60 (as shown in fig. 2f) has not yet reached the desired pressure level, the working machine 4 may continue to deliver gas into the transfer vessel 60 without transferring liquid until the gas contained in the transfer vessel 60 reaches the desired pressure level and another unit of compressed gas 30 is located in the transfer vessel 60 to be delivered into the pressure storage tank 1.

Then, the fluid connection 11 between the working machine 4 and the transfer container 60 is interrupted and a fluid connection 12 between the transfer container 60 and the pressure tank 1 is established and, under the conditions according to fig. 2a, the cycle starts again with changing contents of the pressure tank 1, whereby the unit of compressed gas 30 in the transfer container 60 is transferred into the pressure tank 1. If the unit of compressed gas 30 in the transfer vessel 60 is at the pressure level in the pressure storage tank 1 before the fluid connection 12 is established between the pressure storage tank 1 and the transfer vessel 60, the pressure level in the pressure storage tank 1 will remain constant when the transfer process (fig. 2a to 2f) is repeated. If the pressure level of the unit compressed gas 30 is lower than the pressure level of the pressure storage tank 1 before the fluid connection 12 is established between the pressure storage tank 1 and the transfer vessel 60, the pressure level of the pressure storage tank 1 will decrease. If the pressure level of the unit compressed gas 30 is higher than the pressure level of the pressure storage tank 1 before the fluid connection 12 is established between the pressure storage tank 1 and the transfer vessel 60, the pressure level of the pressure storage tank 1 will increase. Therefore, the pressure level of the pressure storage tank 1 can be controlled during the filling of the compressed gas (irrespective of the filling level of the pressure storage tank 1). Thus, the unit of compressed gas 30 in the transfer vessel 60 is not or only slightly compressed due to the change in liquid level in the transfer vessel 60. Therefore, this mode of operation is referred to as a "compression mode without post-compression".

The process shown in fig. 2g to 2m will be entitled "compressed mode with post-compression". Compressed mode is identified by the fact that: the flow direction of the gas is directed (at least on a time average) from the gas source 5 to the working machine 4. This means that the working machine 4 is driven to compress gas and draw power from the grid 9. The difference from the "compression mode without post-compression" is that the unit compressed gas 30 generated by the working machine 4 in the transfer vessel 60 is not only transferred into the pressure storage tank 1 by raising the liquid level in the transfer vessel 60, but also can be compressed. This is achieved by moving liquid from the sump 7 into the transfer vessel 60 using a liquid pump 61, as shown in fig. 2g and 2h, whereby the unit of compressed gas 30 is enclosed in the transfer vessel 60, i.e. on the gas side, without a fluid connection 11, 12 between the transfer vessel 60 and the pressure storage tank 1 or the working machine 4. When the desired pressure level is reached in the transfer vessel 60, the fluid connection 14 between the sump 7 and the transfer vessel 60 may be interrupted, and a fluid connection 12 may be established between the transfer vessel 60 and the pressure storage tank 1. Fig. 2i to 2m show a subsequent transfer process whereby the unit recompression gas 30 in the transfer vessel 60 is placed in the pressure storage tank 1 and then the unit liquid 20 and the amount of liquid for post-compression are transferred to the sump 7.

This procedure is in principle the same as the procedure described in the operating mode "compression mode without post-compression" (2b to 2f) and is therefore not explained further.

Depending on the application, transfer container 60 may be connected directly to gas source 5, and transfer mechanism 61 may be equipped with drive 8 of work machine 4, so that pre-compression of work machine 4 is not required. In the following, this is referred to as "compression mode with after-compression", even if the transfer device 6 is used to withdraw gas from the gas source 5 and compress this same gas without using the working machine 4 in a pressure storage system.

The process shown in fig. 2n to 2s will be designated as "expansion mode without pre-expansion". This expansion mode is identified by the fact that the flow direction of the gas is directed (at least on a time average) from the working machine 4 to the gas tank 5. This means that the working machine 4 expands the compressed gas and drives the generator 8, whereby electric energy is fed into the electricity network 9. Fig. 2n shows the beginning of the transfer process, wherein the unit of compressed gas 30 located in the pressure storage tank 1 is transferred into the transfer vessel 60. This is done by the liquid pump 61 moving liquid from the transfer vessel 60 into the pressure storage tank 1, where the liquid level rises, thus forcing compressed gas through the fluid connection 12 into the transfer vessel 60, where the unit of compressed gas 30 replaces the unit of liquid 20 that has just been transferred into the pressure storage tank 1. This process is shown in three consecutive time steps in fig. 2n to 2 p. Since the unit liquid 20 and the unit compressed gas 30 are at the same pressure level as the pressure storage tank 1 during this process, the liquid pump 61 only needs to apply a small amount of power (e.g., flow loss, gravity, buoyancy) force) to move the unit liquid 20 and thus the unit compressed gas 30 over a certain time.

Fig. 2q to 2s show a continuation of the process in fig. 2n to 2p, with the liquid 20 in the sump 7 being moved from the sump 7 into the transfer container 60. For this purpose, the fluid connection 12 of the transfer container 60 to the pressure storage tank 1 is interrupted and a fluid connection 11 is established between the working machine 4 and the transfer container 60, so that gas can be transferred from the transfer container 60 into the working machine 4 or can be sucked in. Furthermore, a fluid connection 14 is established between the transfer container 60 and the collecting basin 7, so that the transfer mechanism 61 can transfer liquid from the collecting basin 7 into the transfer container 60. The pressure level at which the gas is located in the transfer vessel 60 is relevant here. For example, if the gas in the transfer vessel 60 is at the pressure level of the gas source 5 and the liquid in the sump 7 is also at the pressure level of the gas source 5, the liquid pump 61 in turn only needs to apply a small amount of power (e.g., flow loss, gravity, buoyancy) to pump the liquid from the sump 7 into the transfer vessel 60 over a period of time. During this process, the higher the pressure difference between the liquid in the transfer container 60 and the liquid in the sump 7, the more power the liquid pump 61 has to apply to pump or brake the liquid, depending on which is the higher the pressure level in the sump 7 or transfer container 60. If the gas contained in the transfer vessel 60 (as shown in fig. 2 q) is not already at the desired pressure level, the working machine 4 may first release gas from the transfer vessel 60 without transferring liquid until the gas contained in the transfer vessel 60 has reached the desired lower pressure level.

After the condition shown in fig. 2s is reached, the fluid connection 11 between the working machine 4 and the transfer vessel 60 is interrupted, the fluid connection 12 between the transfer vessel 60 and the pressure storage tank 1 is opened, and the cycle starts again under the condition shown in fig. 2n as the content of the pressure storage tank 1 changes, whereby the unit of compressed gas 30 in the pressure storage tank 1 is transferred again into the transfer vessel 60. During the withdrawal of the compressed gas, the pressure level of the pressure storage tank 1 remains constant, whereby the unit of compressed gas 30 in the transfer vessel 60 is not or only slightly expanded or compressed due to the liquid level variations in the transfer vessel 60. Therefore, this mode of operation is referred to as "expansion mode without pre-expansion".

The process described in fig. 2t to 2z will be referred to hereinafter as "expansion mode with pre-expansion". This expansion mode is identified by the fact that the flow direction of the gas is directed (at least on a time average) from the working machine 4 to the gas tank 5. This means that the working machine 4 expands the compressed gas and drives the generator 8, whereby electric power is delivered into the grid 9. The difference from the "expansion mode without pre-expansion" is that the unit of compressed gas 30 (as shown in fig. 2t to 2 u) taken from the pressure storage tank 1 and located in the transfer vessel 60 is not only transferred by lowering the liquid level in the transfer vessel 60, but is also capable of expansion. This is achieved by moving liquid from the transfer vessel 60 into the sump 7 using a liquid pump 61, as shown in fig. 2v and 2w, whereby the unit of compressed gas 30 is enclosed in the transfer vessel 60, i.e. on the gas side, without a fluid connection 11, 12 between the transfer vessel 60 and the pressure storage tank 1 or the working machine 4. When the desired pressure level is reached in the transfer container 60, a fluid connection 11 can be established between the transfer container 60 and the working machine 4. Fig. 2x to 2z show a subsequent transfer process whereby the unit of pre-expanded gas 30 in the transfer vessel 60 is transferred to the working machine 4. This process is essentially the same as the operation mode "expansion mode without pre-expansion" (fig. 2q to 2s) and will not be explained further.

The process shown in fig. 2t and 2u can also be performed, if necessary, by replacing the existing fluid connection 13 between the transfer vessel 60 and the pressure storage tank 1 with the existing fluid connection 14 between the transfer vessel 60 and the sump 7. In this case, the pressure level in the pressure vessel 1 may decrease. Alternatively, as shown in fig. 2v and 2w, the procedure is performed by replacing the existing fluid connection 14 between the transfer container 60 and the sump 7 by an existing fluid connection 13 between the transfer container 60 and the pressure storage tank 1. Then, the pressure level in the pressure storage tank rises. Therefore, the pressure level of the pressure storage tank 1 can be controlled during the withdrawal of the compressed gas (regardless of the filling level).

Depending on the application, the transfer container 60 may be directly connected to the gas source 5 and the transfer mechanism 61 may be equipped with the output 8 of the working machine 4, so that no working machine 4 is required for pre-expansion. Hereinafter, the term "expansion mode with pre-expansion" may be used even if the transfer mechanism 6 is used to draw gas from the pressure storage tank 1 and expand the gas without using the working machine 4 in the pressure storage system.

Fig. 3a to 3c are intended to clarify the meaning of a combination of gas and liquid or a separate gas or liquid transfer vessel 60, without finally describing possible combinations of separate or combined transfer vessels. One or more pistons are used as the displacement mechanism 61. The piston and piston rod replace the liquid pump, which is used as the transfer mechanism 61 in fig. 2, 2a to 2 z. The piston movement indicated by the larger arrow is controlled by a piston rod and has an input or output drive, which is not shown in fig. 3a to 3 c. The piston may also perform a separation function to separate media (gas/gas, liquid/liquid). The pressure storage tank 1, the sump 7 and other components, such as the working machine 4, are not shown in fig. 3a to 3c, since they have the same function as shown in the previous figures. The design variants of the illustrated transfer device 6 can be used in the operating modes "compression mode without after-compression" or "compression mode with after-compression" and "expansion mode without pre-expansion" or "expansion mode with pre-expansion". The individual steps of the compression and expansion process correspond to the processes shown in fig. 2a to 2z and are not explained in detail again.

Fig. 3a shows a transfer device 6 comprising a combined gas and liquid transfer container 60 and a piston with a piston rod, which serves as a transfer mechanism 61. The piston may be used to separate gas and liquid. On the gas side, a fluid connection 11 to the working machine 4 or the gas source/sink 5 and/or a fluid connection 12 to the pressure storage tank 1 can be made by the combined transfer vessel 60, while on the liquid side, a fluid connection 13 to the pressure storage tank 1 and/or a fluid connection 14 to the sump 7 can be made.

Fig. 3b shows a transfer device 6 comprising a combined gas and liquid transfer container 60a, a separate liquid transfer container 60b and a piston with a piston rod, which serves as a transfer mechanism 61. The piston may be used to separate liquids. There is a fluid connection between the transfer containers 60a and 60b through which the transfer mechanism 61 can transport liquid in both directions. From the combined transfer container 60a, a fluid connection 11 to the working machine 4 or the gas source/tank 5 and/or a fluid connection 12 to the pressure storage tank 1 can be established on the gas side. A fluid connection 13 to the pressure storage tank 1 and/or a fluid connection 14 to the sump 7 may be established on the fluid side of the liquid transfer vessel 60 b.

Fig. 3c shows a transfer device 6, which transfer device 6 consists of a separate gas transfer container 60a, a separate liquid transfer container 60b and two pistons with piston rods, which serve as transfer means 61. As schematically shown, the pistons are connected by a crank mechanism. Rigid connection of the piston rods is also possible, but for this purpose the transfer containers 60a, 60b have to be arranged in line. The transfer containers 60a and 60b are mechanically connected by a transfer mechanism 61. This enables the liquid and gas to be distributed to two different transfer vessels. Optionally, additional liquid pads may be attached to the piston of the transfer vessel 60a to facilitate desired characteristics and processes, such as controlling heat transfer from and to the gas, or minimizing the dead space volume of the transfer vessel 60 a. On the gas side, a fluid connection 11 to the working machine 4 or the gas source/tank 5 and/or a fluid connection 12 to the pressure vessel 1 can be established from the gas transfer vessel 60 a. On the liquid side, a fluid connection 13 from the liquid transfer vessel 60b to the pressure vessel 1 and/or a fluid connection 14 to the sump 7 can be made.

Fig. 4 shows a possible parallel arrangement of two combined gas and liquid transfer containers 60a, 60b, a separate liquid transfer container 60c and a piston with a piston rod as a moving mechanism 61. The pressure storage tank 1, the sump 7 and other components such as the working machine 4 are not shown in fig. 4, since they have the same function as in the previous figures. A fluid connection may be established between the transfer containers 60a and 60c or 60b and 60c through which the transfer mechanism 61 may transport fluid in both directions. A fluid connection 11 and/or a fluid connection 12 to the pressure storage tank 1 can be made between the transfer containers 60a and 60b on the gas side and the working machine 4 or the gas source/sink 5. A fluid connection 13 to the pressure storage tank 1 and/or a fluid connection 14 to the sump 7 can be made on the liquid side by the liquid transfer vessel 60 c. With this version of the transfer device 6, the transfer mechanism 61 acts alternately on the transfer receptacles 60a and 60 b. As a result, there is more time in the transfer vessels 60a and 60b for the compression or expansion process, with similar performance profiles as the transfer mechanism 61, to facilitate any desired thermodynamic properties and processes, such as optimizing and controlling heat transfer from and to the gas.

Fig. 5 and 6 show a parallel arrangement of the transfer vessels, which allows liquid to be transferred between the transfer vessels 60a, 60b and the pressure storage tank 1 or the sump 7, but also between the transfer vessels 60a, 60b themselves by means of the transfer mechanism 61 in the operating modes "compression mode with after-compression" and "expansion mode with pre-compression". The timing of this process is explained using fig. 6a to 6 y.

The pressure storage tank 1, the sump 7 and other components such as the working machine 4 are not shown in fig. 6a to 6y, since they have the same function as in the previous figures.

Fig. 5 shows a possible parallel arrangement of the transfer containers 60a, 60b and the piston as the transfer mechanism 61. The illustrated transfer mechanism 6 consists of, among other things, two combined gas and liquid transfer containers 60a and 60b, a separate liquid transfer container 60c and a piston with a piston rod, which serves as the transfer mechanism 61. A fluid connection may be established between each transfer container 60a and 60c or 60b and 60c, whereby the transfer mechanism 61 may transfer liquid between the transfer containers 60a and 60b in two directions. A fluid connection 11 from the transfer containers 60a and 60b to the working machine 4 or the gas source/tank 5 and/or a fluid connection 12 to the pressure storage tank 1 can be made on the gas side. A fluid connection 13 to the pressure storage tank 1 and/or a fluid connection 14 to the sump 7 can be made on the liquid side by the liquid transfer vessel 60 c. With this version of the transfer device 6, the transfer mechanism 61 can act alternately on the transfer receptacles 60a and 60b simultaneously.

Fig. 6 and 6a to 6y show a possible parallel design of the transfer containers 60a and 60b and the liquid pump as transfer mechanism 61. From the combined gas and liquid transfer vessels 60a and 60b, a fluid connection 11 to the working machine 4 or the gas source/tank 5 and/or a fluid connection 12 to the pressure storage tank 1 can be made on the gas side. In addition, a fluid connection 13 to the pressure storage tank 1, a fluid connection 14 to the sump 7 and/or a fluid connection between the transfer vessels 60a and 60b can be established on the liquid side. Together with the valves 64 and 65, a valve block 66 consisting of four individual valves makes it possible to define the flow direction of the liquid from/to the transfer containers 60a and 60b, from/to the sump and from/to the pressure storage tank 1 by means of the liquid pump 61. This allows liquid to be transferred in both directions between the transfer vessel 60a or 60b and the pressure storage tank 1, the sump 7 or between the transfer vessels 60a and 60b themselves.

Fig. 6a to 6c show the timing of the compression of the unit gas 30 in the transfer container 60 a. The liquid is moved from the parallel transfer container 60b to the transfer container 60a by the transfer mechanism 61, and the gas 30 is compressed in units. The gas flows into the transfer container 60b through the fluid connection 11. Once the unit gas 30 reaches the desired pressure level, as shown in fig. 6d, fluid connections 12 and 13 are established between the transfer container 60a and the pressure storage tank 1 so as to transfer the unit gas 30 compressed by the transfer mechanism 61 into the pressure storage tank 1 by applying the process already described, thereby taking out the unit liquid 20 from the pressure storage tank 1 so as to transfer the unit gas 30 compressed by low power from the transfer container 60a to the pressure storage tank 1. The completed transfer process is shown in fig. 6e, whereby the unit liquid 20 is located in the transfer container 60a for transfer to the sump 7 by establishing a fluid connection 14 between the transfer device 6 and the sump 7 as shown in fig. 6f and 6 g. Due to the fluid connection 11 established between the transfer device 6 and the working machine 4 or directly with the gas source 5, gas can flow into the transfer container 60 a. As shown in fig. 6h to 6j, the process of compressing the gas 30 per unit in the transfer container 60b is repeated to be transferred into the pressure storage tank 1 as shown in fig. 6k and 6l, thereby taking the liquid 20 per unit out of the pressure storage tank 1 and transferring into the catch basin 7 as shown in fig. 6m and 6 n. Since the processes in fig. 6h to 6n correspond in principle to the processes in fig. 6a to 6g, the processes in fig. 6h to 6n are not explained in detail. Fig. 6o then shows the continuity in time, whereby the state of the transfer device 6 again corresponds to the state in fig. 6a, and the entire process of compressing the gas and introducing the gas into the pressure storage tank 1 can be repeated.

Fig. 6p to 6y show the time sequence for withdrawing the compressed gas 3 from the pressure storage tank 1 and lowering it to a lower pressure level by means of the transfer device 6 in the operation mode "expansion with pre-expansion mode".

Fig. 6p and 6q show the timing sequence for withdrawing a unit of compressed gas 30 from the pressure storage tank 1 by means of the transfer device 6 moving the unit of liquid 20 from the transfer vessel 60a into the pressure storage tank 1 and establishing the fluid connections 12 and 13 between the transfer device 6 and the pressure storage tank 1. As can be seen in fig. 6r to 6t, the fluid connections 12 and 13 between the transfer container 6a and the pressure storage tank 1 are then disconnected and a fluid connection between the transfer containers 6a and 6b is established by means of the switching valve 66, whereby liquid is displaced in a controlled manner into the transfer container 60b by means of the displacement mechanism 61, expanding the unit of compressed gas 30 in the transfer container 60 a. The expanded gas in the transfer vessel 60b is delivered to the working machine 4 via the fluid connection 11 or directly to the gas tank 5. As shown in fig. 6u and 6v, after the desired pressure level is reached in the transfer vessel 60a, a fluid connection 14 is also established between the transfer vessel 60b and the sump 7 via a switching valve 66, in order to transfer the amount of liquid corresponding to the unit liquid 20 from the sump 7 to the transfer vessel 60b via the transfer mechanism 61, in order to take the unit gas 30 from the pressure storage tank 1. Then, as shown in fig. 6w and 6x, fluid connections 12 and 13 are established between the transfer container 60b and the pressure storage tank 1 through the switching valve 66, so that the unit liquid 20 is transferred from the transfer container 60b to the pressure storage tank 1 by using the transfer mechanism 61 to take the unit gas 30 from the pressure storage tank 1. Then, as shown in fig. 6y, the unit gas 30 in the transfer container 60b is expanded in the same manner as in fig. 6r to 6 t. As can be understood from the above description, the process and the re-evacuation of the further unit of gas from the pressure storage tank 1 and the expansion of the unit in the transfer vessel 60a will not be discussed in detail.

In the operating modes "compression mode with after-compression" and "expansion mode with pre-expansion", a multistage or series arrangement is meaningful. The advantage of delivering compressed gas into the pressure storage tank 1 or withdrawing compressed gas from the pressure storage tank 1 by means of the transfer device 6 has been explained in the foregoing. However, it is also possible to apply the same transfer process between two different pressure levels within the transfer device 6. In the following, it is referred to as first stage and second stage, whereby further stages can be added according to the same principle.

Fig. 7 and 7a to 7n explain in more detail the working of the transfer device 6, without showing the other components of the pressure storage system as shown in fig. 1, since their function is not changed.

Fig. 7 and fig. 7a to 7n show possible parallel and serial designs of the transfer vessel and of two liquid pumps 61a and 61b as transfer means, whereby the transfer process is applied between the second stage and the pressure storage tank 1 and between the first stage and the second stage. The first stage consists of two transfer vessels 60a and 60b, a transfer mechanism 61a and corresponding valves. Thus, the second stage includes a transfer container 60c, a transfer mechanism 61b and corresponding valves. On the gas side, the transfer mechanism may be connected to the working machine 4 or the gas source/tank 5 via a fluid connection 11 and to the pressure storage tank 1 via a fluid connection 12. On the liquid side, the transfer device 6 may be connected to the pressure storage tank 1 via a fluid connection 13 and to the sump 7 via a fluid connection 14.

Fig. 7a and 7b show a timing sequence for compressing the unit gas 30b inside the transfer container 60c by transferring liquid from the transfer container 60b into the transfer container 60c using the transfer mechanism 61 b. At the same time, the liquid is transferred from the transfer container 60b to the transfer container 60a by the transfer mechanism 61a, and the unit gas 30a is also compressed in the transfer container 60 a. When the desired pressure level is reached in the transfer vessel 60c, as shown in fig. 7c and 7d, the unit compressed gas 30b is transferred from the transfer vessel 60c to the pressure vessel 1 by transferring the unit liquid 20 from the pressure storage tank 1 to the transfer vessel 60c using the transfer mechanism 61 b. At the same time, the unit gas 30a is further compressed in the transfer vessel 60a until the desired pressure level is reached. Then, as shown in fig. 7e and 7f, the unit compressed gas 30a is moved into the transfer container 60c by transferring the unit liquid 20a from the transfer container 60c into the transfer container 60a using the transfer mechanism 61 a. At the same time, the amount of unit liquid 20 is transferred correspondingly from the displacement container 60b via the fluid connection 14 into the collecting basin 7 by means of the transfer mechanism 61 b.

Fig. 7g shows an initial state of the transfer mechanism 6 in which the unit gas 30a is compressed in the transfer container 60c and introduced into the pressure storage tank, another unit of the gas 30c is compressed in the transfer container 60b, and then, transferred into the transfer container 60c, similarly to the process shown in fig. 7a to 7 f.

Fig. 7h to 7n show the sequence of discharging the compressed gas 3 from the pressure storage tank 1 by means of the transfer device 6 and lowering it to a lower pressure level in the operating mode "expansion mode with pre-expansion".

Fig. 7h and 7i show the withdrawal of unit of compressed gas 30b from the pressure storage tank 1 by means of the transfer device 6 moving the unit of liquid 20b from the transfer vessel 60c into the pressure storage tank 1 and establishing fluid connections 12 and 13 between the transfer device 6 and the pressure storage tank 1. At the same time, the liquid is transferred from the transfer container 60a to the transfer container 60b in a controlled manner by the transfer mechanism 61a, causing the unit gas 30a to expand in the transfer container 60 a. As shown in fig. 7j and 7k, the unit gas 30a in the transfer vessel 60a is further expanded until the desired pressure level is reached. At the same time, moving the liquid from the transfer vessel 60c to the transfer vessel 60b, also via the transfer mechanism 61b, expands the unit of compressed gas 30b located in the transfer vessel 30c until the desired pressure level is reached. Then, as shown in fig. 7l and 7m, the unit inflation gas 30b is moved from the transfer container 60c into the transfer container 60b by transferring the liquid 20b from the transfer container 60b into the transfer container 60c using the transfer mechanism 61 a. Fig. 7n shows an initial state of the transfer device 6, followed by the expansion of the unit gas 30b in the transfer container 60b, and the transfer of the unit liquid 20c from the transfer container 60c to the pressure storage tank 1 by the transfer mechanism 61b, and further withdrawal of the unit gas from the pressure storage tank 1 and transfer thereof to the transfer container 60c, similar to the process shown in fig. 7h to 7 m.

Fig. 8 shows a possible separation device 31 for separating the liquid 2 and the compressed gas 3 in the pressure storage tank 1. The separator 31 is here designed, for example, as a gas bubble, which can change its shape to adapt to the filling level of the pressure storage tank 1. Of course, this function may also be performed by other types of separators, such as pistons. Separation of the liquid 2 from the gas 3 may be necessary to limit the amount of dissolved gas in the liquid or to allow any orientation of the pressure storage tank 1, regardless of the direction of forces such as gravity or buoyancy.

Fig. 9 shows a possible arrangement of a heat accumulator 69 and/or a heat exchanger 68 in the transfer vessel 60, which heat accumulator 69 and/or heat exchanger 68 is used to remove heat which is removed from the gas in the transfer vessel 60 via the heat exchanger 68 and/or transferred to the liquid via the heat accumulator 69, or vice versa, heat being supplied via the heat exchanger 68 and/or transferred from the liquid to the gas via the heat accumulator 69.

Fig. 10 shows an energy storage system as shown in fig. 1, with the difference that the sump 7 is connected to the working machine 4 by a fluid connection 15 and can therefore be at any pressure level. If the transfer device 6 is used only for compression or expansion of gas in the energy storage system, and the working machine 4 is not used, the sump 7 is connected to the transfer device 6 by a fluid connection 15 to control the pressure level in the sump 7.

Fig. 11 shows the pressure vessels 101, 102,. combined into a pressure storage tank 1. This arrangement increases the energy density of the pressure storage system by reducing the amount of liquid compared to the pressure storage tank capacity.